For several years now, research, including groundbreaking work done at the American Cancer Society, has sounded the alarm about cancer risk associated with time spent sitting. Now a new study co-authored by Alpa Patel, PhD, who also led earlier work on the link, digs deeper to find spending more leisure time sitting is associated not only with a higher risk of total cancer risk in women, but also with several cancers in particular: multiple myeloma, breast, and ovarian cancer.

And for reasons that are as yet unclear, the study found no such association for men.

The link between physical activity and cancer prevention is well-established. But emerging evidence has focused specifically on the link between time spent sitting and cancer. That includes time spent sitting at work, and also leisure time. In both cases, time spent sitting has increased due to several factors, including technological advancements, like computers and video games, and changes in transportation; we walk/bike less, and drive/ride more.

For the current study, investigators compared leisure time sitting to cancer risk among more than 146,000 men and women (69,260 men and 77,462 women) who were cancer-free and enrolled in the American Cancer Society Cancer Prevention Study II Nutrition Cohort. During the time of the study, (1992 – 2009), 18,555 men and 12,236 women were diagnosed with cancer.

The investigators found more leisure-time spent sitting was associated with a 10 percent higher risk of cancer overall in women after adjustment for physical activity, BMI and other factors..

In women, sitting time was associated with a 65 percent increased risk of multiple myeloma, a ten percent increase in risk of invasive breast cancer, and a 43 percent increase in risk of ovarian cancer. In men, just as with cancer overall, there was no association between overall or site-specific cancers and sitting time.

American Cancer Society guidelines for cancer prevention recommend reducing sitting time when possible. The authors say given the high rate of time spent sitting in the U.S., even a modest positive association with cancer can have broad public health implications.

“Our bodies were built to move, but our lifestyles today sometimes make that difficult to do,” said Dr. Patel. “Making simple changes like folding laundry while watching TV, or parking farther away from the entrance to a store can cut down on time you are sitting. Ultimately, these little changes can have a big impact on your health.”

Dr. Patel adds that further research is warranted to better understand the differences in associations between men and women, and that work could shed light on the reasons for link.

Article: Leisure-time spent sitting and site-specific cancer incidence in a large US cohort; Cancer Epidemiol Biomarkers Prev. [Epub ahead of print] Published Online First June 30, 2015; doi: 10.1158/1055-9965.EPI-15-0237